Car starts, but won't stay running

[FOCOCO]

Hi everyone, new to this. I have a 99 Subaru legacy GT limited, 2.5 L. Recently it began to idle low and die when stopped. It was fine while actually driving. We changed the fuel filter, fuel pump, and air filter. Now, the car starts, but won't stay running. It dies after a few seconds. The check engine light is on and the code that came up for that was the knock sensor, but from what I've read, it doesn't seem like the knock sensor would cause it to not stay running. Any ideas would be appreciated. 

Edited July 8, 2016 by FOCOCO

[Bright1]

FOCOCO: FYI, my 96 Legacy 2.2 recently died at idle on 3 separate occasions at stop lights and at idle. The first 2 times I popped it into neutral, turned off the A/C and luckily it restarted right away. The third time it did NOT restart for about a minute, leaving me sitting in an intersection with the 4-way flashers on -- how embarrassing! ;-)  

 

When it did restart the 3rd time, the Check Engine Light remained on, but I was able to drive the remaining mile to my home.  The next day, I drove 2 miles to Advance Auto Parts, borrowed their OBDII tester, and the code came up as a defective Crankshaft Position Sensor.  I cleared the code, but that store was out of stock on the part I needed.  I drove home, bought the part online at a different AAP store with a 20% off coupon code (https://www.retailmenot.com/view/advanceautoparts.com -- final cost $23.73 with tax), drove 4 miles to pick it up without stalling or throwing the CEL code again, installed it in the parking lot (carefully on a hot engine, takes just a 10mm wrench), and everything's run fine since.  

 

Hope that helps... 

[FOCOCO]

FOCOCO: FYI, my 96 Legacy 2.2 recently died at idle on 3 separate occasions at stop lights and at idle. The first 2 times I popped it into neutral, turned off the A/C and luckily it restarted right away. The third time it did NOT restart for about a minute, leaving me sitting in an intersection with the 4-way flashers on -- how embarrassing! ;-)  

 

When it did restart the 3rd time, the Check Engine Light remained on, but I was able to drive the remaining mile to my home.  The next day, I drove 2 miles to Advance Auto Parts, borrowed their OBDII tester, and the code came up as a defective Crankshaft Position Sensor.  I cleared the code, but that store was out of stock on the part I needed.  I drove home, bought the part online at a different AAP store with a 20% off coupon code (https://www.retailmenot.com/view/advanceautoparts.com -- final cost $23.73 with tax), drove 4 miles to pick it up without stalling or throwing the CEL code again, installed it in the parking lot (carefully on a hot engine, takes just a 10mm wrench), and everything's run fine since.  

 

Hope that helps... 

Thanks Bright1! We tried and installed a new crankshaft position sensor today hoping it would work, however, sadly it didn't. The car still has no problem starting, just wont stay on. Very frustrating! Other ideas we may have are idle air control valve, fuel pressure regulator, fuel pump relay/fuse, or someone we know suggested the timing belt. 

[porcupine73]

You're sure there's no air intake tubing that got unhooked? There's usually a hose to each valve cover and then if it's MAF based there's a slightly bigger one that goes to the iacv. Often when working on stuff one or more of those will come unhooked and not get noticed, which can cause issues because it lets unmetered air in (if yours has a MAF, that year/model I think still did with the MAP/speed density starting around 2000)/.

 

I had a '96 Legacy 2.2L before, and yes that same scenario about the crankshaft position sensor happened to me.

Edited July 9, 2016 by porcupine73

[Cougar]

Check the intake manifold gaskets for an air leak along with clean the EGR and idle air valves.

[FOCOCO]

Thanks for the help, everyone. Think we found the problem. Bad MAF sensor. Took it off and car stayed on just fine.